Apparatus for obstacle traversion

ABSTRACT

An apparatus for traversing obstacles having an elongated, round, flexible body that includes a plurality of drive track assemblies. The plurality of drive track assemblies cooperate to provide forward propulsion wherever a propulsion member is in contact with any feature of the environment, regardless of how many or which ones of the plurality of drive track assemblies make contact with such environmental feature.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 09/821,867 filed on Mar. 30, 2001 now U.S. Pat. No. 6,512,345.The disclosure of the above application is incorporated herein byreference.

STATEMENT OF GOVERNMENTAL SUPPORT

This invention was made with Government support under Award No.DE-FG04-86NE3796 awarded by the U.S. Department of Energy. TheGovernment has certain rights in this invention.

FIELD OF THE INVENTION

The present invention generally relates to an apparatus for traversingobstacles and, more particularly, to an apparatus for traversingobstacles having an elongated, flexible body, and a drive trackpropulsion system.

BACKGROUND OF THE INVENTION

Robotic vehicles are often used to navigate or traverse varying terrain.As is well known, wheeled robotic vehicles, both large and small, areparticularly well adapted for travel over relatively smooth terrain,such as roads and smooth floors. However, it is often necessary forrobots to traverse terrain that is not smooth, such as stairs or curbs.Moreover, it is often necessary for robots to traverse terrain that maypose a danger to humans, such as those situations presenting anenvironmental risk, military risk, or the like. Often robotic devicesare useless in these dangerous situations because of their inability tosuccessfully and reliably traverse any severely broken and/or fracturedground that they may encounter. Attempts have been made to overcome thenumerous disadvantages of wheeled robotic vehicles in these situationsby simply increasing the diameter of the wheels or adding tank crawlertracks to increase the ability of the robotic device to traverse largeobjects or spans. However, these solutions include additionaldisadvantages, such as increasing the overall size of the vehicle, whichmay inhibit the robot's ability to pass through small openings.

Furthermore, many robots suffer from being rendered immobile as a resultof a rollover or other situation that prevents contact of theirpropulsion member(s) on the ground surface. That is, should a wheeledrobot encounter a grade sufficient to roll it on its side, the wheelsare no longer capable of propelling the robot. In terrains that pose arisk to humans, such rollovers may render the robot unrecoverable.

Accordingly, there exists a need in the relevant art to provide anapparatus capable of traversing severely broken and/or fractured ground.Further, there exists a need in the relevant art to provide an apparatuscapable of traversing severely broken and/or fractured ground withoutunduly limiting the ability to pass through small openings. Stillfurther, there exists a need in the relevant art to provide an apparatuscapable of engaging its environment at any point about its periphery tominimize the possibility of the apparatus becoming immobile.Furthermore, there exists a need in the relevant art to provide anapparatus for traversing obstacles that overcomes the disadvantages ofthe prior art.

SUMMARY OF THE INVENTION

According to the principles of the present invention, an apparatus fortraversing obstacles having an advantageous design is provided. Theapparatus includes an elongated, round, flexible body that includes aplurality of drive track assemblies. The plurality of drive trackassemblies cooperate to provide forward propulsion wherever a propulsionmember is in contact with any feature of the environment, regardless ofhow many or which ones of the plurality of drive track assemblies makecontact with such environmental feature.

Further areas of applicability of the present invention will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples, whileindicating the preferred embodiment of the invention, are intended forpurposes of illustration only and are not intended to limit the scope ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a perspective view illustrating an apparatus for traversingobstacles according to a first embodiment of the present invention;

FIG. 2 is a side view illustrating the apparatus;

FIG. 3 is a front view illustrating the apparatus;

FIG. 4 is an enlarged perspective view illustrating the actuation of ajoint between two segments of the apparatus;

FIG. 5 is a perspective view illustrating an articulating leg mechanismaccording to the principles of the present invention;

FIG. 6 is a perspective view of a universal coupling interconnectingdrive shafts of adjacent segments of the apparatus;

FIG. 7 is a perspective view of a transmission for transmitting powerfrom the drive shaft to the drive leg mechanism;

FIG. 8 is a perspective view of the transmission of FIG. 7 havingportions removed for clarity;

FIG. 9 is a schematic view illustrating the motion trajectory of thearticulating leg mechanism according to the principles of the presentinvention;

FIG. 10 is a perspective view of an articulating joint according to theprinciples of the present invention; and

FIG. 11 is a perspective view illustrating an apparatus for traversingobstacles according to a second embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The following description of the preferred embodiment is merelyexemplary in nature and is in no way intended to limit the invention,its application, or uses.

Referring to the drawings, an apparatus 10 for traversing obstaclesaccording to a first embodiment of the present invention is illustratedhaving a plurality of identical segments 12. Each of the plurality ofsegments 12 includes a plurality of articulating leg mechanisms 14disposed about the periphery of each segment 12. According to thepresent embodiment, each of the plurality of segments 12 includes fourarticulating leg mechanisms 14 evenly spaced at 90° intervals about theperiphery of each segment 12 to provide a generally continuous series ofpropulsion members. However, it is anticipated that any number ofarticulating leg mechanisms may be used so long as they generally extendaround the outer diameter or periphery of each segment 12. Bypositioning articulating leg mechanisms 14 continuously about theperiphery of segment 12, apparatus 10 is more likely to engage a featurewithin the environment to provide reliable locomotion. This ability toengage an environmental feature, whether it be the ground surface, wallprotrusion, ceiling cavity, or the like, irrespective of its physicalorientation provides apparatus 10 with a reliable means of continuedpropulsion. Adjacent segments 12 are joined together via an articulatingjoint 16 and a drive shaft 18.

Apparatus 10 may include any number of identical segments 12 connectedto each other in a serial fashion. The number of segments 12 requireddepends on the terrain that must be covered. Moreover, as a result oftheir identical construction, segments 12 may be easily added, removed,or exchanged with other robots. For illustration and discussionpurposes, the figures contained herein comprise nine individual segments12.

Referring in particular to FIGS. 4 and 5, each of the plurality ofarticulating leg mechanisms 14 includes a leg 20, a foot 22, a drivengear 24, and a drive gear 26. As can be seen in FIG. 4, articulating legmechanism 14 includes only one degree of freedom, providing a simplifiedpropulsion system. That is, by having only one degree of freedom perleg, instead of the multiple degrees of freedom like many other leggedvehicles, the number of required actuators is reduced, thereby reducingthe weight, complexity, and cost of apparatus 10.

As best seen in FIG. 3, foot 22 is generally arcuate in shape so as tobe generally complimentary to an overall outer shape of apparatus 10.However, the radius of curvature of each foot 22 is preferably less thanthe radius of curvature of a circle C (FIG. 3) swept around apparatus 10and intersects the outermost point of each foot 22. This arrangementminimizes the potential for sideways rolling of apparatus 10. However,as described above, should apparatus 10 nonetheless rollover, at leastsome of articulating leg mechanisms 14 disposed about the periphery ofeach segment 12 will engage a feature of the environment for continuedlocomotion.

The trajectory of foot 22 is determined by the mechanism illustrated inFIG. 5. Specifically, driven gear 24 enmeshingly engages drive gear 26.Driven gear 24 includes a pivot pin 28 that is operably received withinan aperture 30 of leg 20. Similarly, drive gear 26 includes a cam pin 32that is operably received within a cam slot 34 of leg 20. As driven gear24 rotates in a first direction and thereby drives drive gear 26 in anopposite direction, pivot pin 28 acts within aperture 30 to drive leg 20in an extending and retracting motion. Simultaneously, cam pin 32cammingly engages cam slot 34 and drives leg 20 in a sweeping,shoveling, or rotating motion, as illustrated in FIG. 9. Thus, thetrajectory of foot 22 generally includes a lowered portion that is incontact with the ground surface for applying a propelling force to moveapparatus 10 and a raised portion that is not in contact with the groundsurface to allow for forward placement of foot 22 without interferingwith the propelling force applied by other feet 22.

Apparatus 10 further includes a “head” segment 36. Head segment 36 isidentical to segment 12; however, head segment 36 further includes aplurality of sensors 38 (only one shown) and an onboardcomputer/controller 40. The plurality of sensors 38 may be used togather environmental data, surveillance data, or any number of otheruses. Onboard computer 40 is used to control the movement of apparatus10 and to provide a means of controlling and/or communicating with thevarious systems of apparatus 10. To this end, onboard computer 40preferably includes a controller area network (CAN) interface. Inoperation, onboard computer 40 receives environmental data, surveillancedata, or any number of other data from other onboard sensors locatedthroughout apparatus 10. The data is then carried to onboard computer 40via a serial CAN bus. The CAN may then be used to provide a controlsignal to the plurality of articulating leg mechanisms 14 of apparatus10. This arrangement reduces the number of electrical wires neededthroughout apparatus 10. The mechanical operation of head segment 36 isidentical to that of segments 12. Therefore, in the interest of brevity,only a single segment 12 will be discussed in detail, except asotherwise noted.

Apparatus 10 further includes drive shaft 18. Drive shaft 18 providesinput power to each of the plurality of articulating leg mechanisms 14via a transmission 42 disposed in each segment 12. Drive shaft 18 is asingle drive shaft that kinematically links each segment 12 and, moreparticularly, each articulating leg mechanism 14. To this end, driveshaft 18 includes a universal joint 44 (FIG. 6) that allows powertransfer independent of the relative orientation of segments 12. Thisarrangement enables all articulating leg mechanisms 14 to be driven by asingle actuator, generally indicated at 45, which supplies torque todrive shaft 18. It should be appreciated that since all articulating legmechanisms 14 are kinematically linked by single drive shaft 18, thephase differences between each articulating leg mechanism 14 are fixed.That is, the phase relationship of articulating leg mechanisms 14, whichdefines the gait of apparatus 10, will remain whatever it was when therobot was assembled.

The use of single actuator 45 for supplying power to all articulatingleg mechanisms 14 has numerous advantages. Firstly, actuator 45 can beplaced on a specially designed segment (not shown) at the tail end ofapparatus 10 in such a way as to minimize the load on articulating legmechanisms 14, thus reducing the required size of the actuator.Secondly, multiple actuators weigh more than a single actuator thatproduce the same amount of power, thus the overall weight of apparatus10 is reduced by using a single actuator for all articulating legmechanisms 14. Thirdly, the use of high energy density power sources,such as a small gasoline engine, might be feasible. The energy densityof a small gasoline engine with tank is about one order of magnitudegreater than that of a comparable electric motor with lithium-ionbattery.

Referring now to FIGS. 7 and 8, transmission 42 interconnects driveshaft 18 with an input shaft 62 of each articulating leg mechanism 14 ofeach segment 12. Transmission 42 includes an inner spur gear 50 that isfixedly coupled to drive shaft 18 for rotation therewith. Inner spurgear 50 meshes with two idler spur gears 52 (only one shown), which eachmesh with an outer spur gear 54 (only one shown). Outer spur gear 54 isfixedly coupled to a shaft 56. Also fixedly coupled to shaft 56 is aworm gear 58. Worm gear 58 meshes with two worm gears 60. Each of thesefour worm gears 60 is fixedly coupled to input shaft 62 of articulatingleg mechanism 14. Input shaft 62 is fixed for rotation with drive gear26, which thus drives driven gear 24 and rotates leg 20 and foot 22through a five-bar geared mechanism as described above to produce thetrajectory illustrated in FIG. 9. Alternatively, inner spur gear 50 andouter spur gear 54 may each be replaced with a pulley and belt systemfor power transfer.

Adjacent segments 12 of apparatus 10 are connected using articulatingjoints 16 (FIGS. 4 and 10). Specifically, for discussion purposes,adjacent segments 12 will be referred to as segment 12 a and segment 12b in FIG. 10 only. Although, it should be appreciated that segments 12 aand 12 b are identical in construction. Each articulating joint 16comprises two revolute joints, generally indicated as axis A and axis B,whose axes intersect at an intersection point of articulating joint 16.These two revolute joints are separated by 90° to provide the twodegrees of freedom. As best seen in FIG. 10, these two degrees offreedom are each independently controlled with an actuator or pneumaticpiston 64 a and 64 b (generally indicated as 64 elsewhere). Each segment12 a and 12 b include a pair of arm supports 66 extending from endsurfaces 68 thereof (FIGS. 7 and 10). The pair of arm supports 66 arepivotally journalled to a floater bracket 70 via a pair of pivot pins72. Articulation of joint 16 about axis A is caused when actuator 64 a,which is mounted on segment 12 a, pushes or pulls a bracket 74 a bymeans of a rotating crank 76 a. Accordingly, this actuation rotatessegment 12 a relative to floater bracket 70 about axis A.

Similarly, articulation of joint 16 about axis B is caused when actuator64 b, which is mounted on segment 12 b, pushes or pulls a bracket 74 b(located on a backside in FIG. 10) by means of a rotating crank 76 b(located on a backside in FIG. 10). Accordingly, this actuation rotatessegment 12 b relative to floater bracket 70 about axis B. Actuators 64 aand 64 b enable apparatus 10 to lift its front end on top of obstacles.This allows apparatus 10 to adjust to the contour of the terrain andovercome obstacles that are orders of magnitude larger than its stepheight.

A skin (not shown) may be applied around apparatus 10 to protect allinternal parts from moisture or sand. However, in some applications, askin may not be necessary.

As best seen in FIGS. 2 and 3, apparatus 10 is illustrated as walking ona flat surface, for a simplified discussion model. However, it should beunderstood that apparatus 10 is capable of traversing rough terrain. Asseen in FIG. 3, the front view of apparatus 10 shows that feet 22 ofsegment 12 touch the ground at two contact points A and B. This is dueto the fact that the radius of curvature of feet 22 is smaller than theoverall radius of curvature of apparatus 10, thereby producing generallyflat surfaces extending between the ends of adjacent feet 22 on a singlesegment 12 (see FIG. 3). This arrangement reduces the tendency of theotherwise cylindrical robot (when all segments are aligned) to roll.However, it should be understood that these contact points may be at anypoint about the periphery of apparatus 10. For instance, shouldapparatus 10 span a fractured ground or fractured pipe, feet 22 ofarticulating leg mechanism 14 may engage a feature along the ceilingthereof to provide locomotion. Moreover, should apparatus 10 traverse acontinuous pipe that is only slightly larger in diameter than apparatus10, then all feet 22 disposed about each segment 12 would engage thewalls thereof. Thus, each segment 12 may have multiple simultaneouscontact points.

The particular gaits of apparatus 10 will now be described with generalreference to FIG. 2, which illustrates a worm-like gait. For purposes ofdiscussion, head segment 36 will be referred to as segment one while thelast segment will be referred to as segment nine and the remainingsegments numbered consecutively therebetween. Furthermore, the two feet22 that are contacting the ground at each segment will be referred to asthe right and left feet as apparatus 10 faces forward.

FIG. 2 illustrates a worm-like gait in that the plurality ofarticulating leg mechanisms 14 disposed on each segment 12 aresynchronized to provide a simultaneous driving motion. That is,accordingly to the worm-like gate, all leg mechanisms 14 on a givensegment 12 are in phase with the other leg mechanisms 14 on that givensegment 12. However, adjacent segments 12 are out of phase with eachother. For example, to achieve a worm-like gait, the left and right feetof segment one would be in a pre-driving position, the left and rightfeet of segment two would be in a driving position in contact with theground surface, and the left and right feet of segment three would be ina post-driving position (see FIG. 2). Such a worm-like gait isparticularly useful for burrowing and/or tunneling into soil.

Alternatively, an alternating tripod gait may be used and isparticularly useful for traversing an above-ground surface. According tothis alternating tripod gait, the right foot of segments one and seven,and the left foot of segment four all touch the ground simultaneously ingenerally a triangular pattern. The left foot of segments two and eight,and the right foot of segment five will be the next to touch the ground,and so forth. Accordingly, it should be appreciated that unlike theaforementioned worm-like gait, each articulating leg mechanism 14 is180° out of phase with the adjacent leg mechanism of the same segment.This arrangement provides a very stable tripod support structure.

It should be appreciated that the particular gait employed depends, inpart, on the terrain encountered. It is anticipated that onboardcomputer 40 and articulating leg mechanism 14 of apparatus 10 could beadapted to change the gait of apparatus 10 in accordance with theenvironmental conditions experienced.

Turning now to FIG. 11, an apparatus 110 for traversing obstaclesaccording to a second embodiment of the present invention is illustratedhaving a plurality of identical segments 112. It should be appreciatedthat apparatus 110 is similar in construction to apparatus 10.Therefore, in the interest of brevity, only those areas that differ willbe discussed in detail herein.

Each of the plurality of segments 112 includes a plurality of drivetrack assemblies 114 disposed about the periphery of each segment 112.Preferably, drive track assemblies 114 are arranged in pairs on each ofthe four sides of apparatus 110. However, it should be understood that asingle drive track assembly may be used on each of the sides ofapparatus 110. Specifically, according to the present embodiment, eachof the plurality of segments 112 includes four pairs of drive trackassemblies 114 evenly spaced at 90° intervals about the periphery ofeach segment 112 to provide a generally continuous series of propulsionmembers. By positioning drive track assemblies 114 continuously aboutthe periphery of segment 112, apparatus 110 is more likely to engage afeature within the environment to provide reliable locomotion. Thisability to engage an environmental feature, whether it is the groundsurface, wall protrusion, ceiling cavity, or the like, irrespective ofits physical orientation provides apparatus 110 with a reliable means ofcontinued propulsion. Adjacent segments 112 are joined together viaarticulating joint 16 and drive shaft 18.

Apparatus 110 may include any number of identical segments 112 connectedto each other in a serial fashion. The number of segments 112 requireddepends on the terrain that must be covered. Moreover, as a result oftheir identical construction, segments 112 may be easily added, removed,or exchanged with other robots. For illustration and discussionpurposes, the figures contained herein comprise nine individual segments112.

Still referring to FIG. 11, a transmission 142 interconnects drive shaft18 with each drive track assembly 114 of each segment 12. Transmission142 is similar to transmission 42 and includes a worm gear 158 driven inresponse to drive shaft 18. Worm gear 158 meshes with each drive trackassembly 114 in an identical arrangement. Therefore, only one completetransmission system will be described. Worm gear 158 meshes with a firstspur gear 170, which in turn meshes with a second spur gear 172. Secondspur gear 172 meshes with a third spur gear 174. Third spur gear 174 isfixed to a track drive shaft 176 to drive track drive shaft 176 inresponse to rotation of third spur gear 174. Track drive shaft 176preferably extends to both sides of third spur gear 174 and is fixed toa pair of driven gears 178 for rotation with track drive shaft 176. Eachof the pair of driven gears 178 engages a corresponding rack 180disposed along an inner surface of a flexible track member 182. Flexibletrack member 182 includes engaging treads 184 disposed along an outersurface thereof for engaging an environmental feature. Flexible trackmembers 182 are driven around driven gear 178 and an alignment gear 184disposed at an opposing end of track member 182. It should be understoodthat alignment gear 184 is not separately driven, but instead rotates inresponse to the driving of track member 182. Accordingly, each of thepair of track members 182, which are disposed on each side of apparatus110, are driven by drive shaft 18 to ensure proper and reliablelocomotion.

Preferably, the four pairs of drive track assemblies 114 disposed oneach segment 112 are driven continuously such that if apparatus 110rolls over, it can continue to be driven. However, it is anticipatedthat each pair of drive track assemblies 114 may be independentlyactuated to enable only a selective pair of drive track assemblies 114to be used at any one time. This would enable power consumption to bereduced in applications requiring onboard power storage and prolongedoperation. To this end, computer/controller 40 and at least one of theplurality of sensors 38 may be used to determine orientation ofapparatus 110 and output a control signal. In response to this controlsignal, an engagement mechanism can be actuated to disengage first spurgear 170 from worm gear 158 or second spur gear 172 from first spur gear170. The engagement mechanism may be a solenoid operated actuatorcapable of pivoting first spur gear 170 or second spur gear 172 out ofengagement to enable track members 182 to rotate freely so as not toinhibit locomotion. It should be understood that other engagement and/orclutching devices may be used.

Accordingly, the apparatus of the present invention may find utility ina wide variety of applications. By way of non-limiting example,apparatus 10, 110 may be used for fully autonomous search for survivorsof earthquakes underneath the rubble of collapsed buildings; militaryapplications in very rugged terrain; mining and autonomous search forother natural resources in terrain that is not accessible to humans(i.e., jungles, mountains, etc.); autonomous burrowing in soft soil;monitoring potential underground radiation leakage of buried radioactivewaste; nuclear disaster cleanup (e.g., Chernobyl) and sample retrieval;or research platform for studying many-legged locomotion. An additionalbenefit of using a plurality of pairs of drive track assemblies is thespeed at which apparatus 110 can be propelled and the simple andreliable construction thereof.

The description of the invention is merely exemplary in nature and,thus, variations that do not depart from the gist of the invention areintended to be within the scope of the invention. Such variations arenot to be regarded as a departure from the spirit and scope of theinvention.

What is claimed is:
 1. An apparatus comprising: a plurality of segments;a plurality of articulating joints individually interconnecting at leasta portion of said segments; a plurality of drive track assembliesoperably coupled to each of said plurality of segments, said pluralityof drive track assemblies generally disposed about a periphery of eachof said plurality of segments to provide traction at any position aboutsaid periphery; a power source; and a power transmission systeminterconnecting said power source and at least a portion of said drivetrack assemblies to drive said at least a portion of said drive trackassemblies.
 2. The apparatus according to claim 1 wherein each of saidplurality of drive track assemblies comprises: a continuous drive track;a drive gear operably coupled to said power transmission system; adriven gear enmeshingly engaging said drive gear; and a track gear fixedfor rotation with said driven gear, said track gear enmeshingly engagingsaid continuous drive track to drive said continuous drive track topropel the apparatus.
 3. The apparatus according to claim 1 wherein eachof said plurality of drive track assemblies comprises: a continuousdrive track having an environment engaging outer surface and a rackedinner surface; a worm gear operably coupled to said power transmissionsystem; a first gear enmeshingly engaging said worm gear; a second gearenmeshingly engaging said first gear; a third gear enmeshingly engagingsaid second gear, said third gear having a drive shaft fixed thereto forrotation therewith; and a pair of driven gears fixed to said drive shaftfor rotation with said drive shaft, each of said pair of driven gearsengaging said racked inner surface of said continuous drive track todrive said continuous drive track.
 4. The apparatus according to claim 1wherein a pair of said plurality of drive track assemblies is disposedon each of four sides of each of said plurality of segments to providetraction at any position about said periphery.
 5. The apparatusaccording to claim 1 wherein said plurality of segments is identical andinterchangeable.
 6. The apparatus according to claim 1, furthercomprising: a head segment coupled to one of said plurality of segments;and a controller mounted in said head segment, said controller drivingsaid plurality of drive track assemblies.
 7. The apparatus according toclaim 6 wherein each of said pair of drive track assemblies isindependently actuated in response to said controller to provideselective propulsion along only a pair of said plurality of drive trackassemblies.
 8. The apparatus according to claim 6, further comprising: asensor system for gathering data, said sensor system being incommunication with said controller.
 9. The apparatus according to claim1 wherein said power transmission system comprises: a plurality of drivemembers individually extending through each of said plurality ofsegments, each of said plurality of drive members driving at least acorresponding one of said plurality of drive track assemblies; and aplurality of universal joints pivotally interconnecting said pluralityof drive members in series, thereby defining a continuous drive traindriven by said power source.
 10. The apparatus according to claim 1wherein each of said plurality of articulating joints includes at leasttwo degrees of freedom, each of said degrees of freedom being actuatedby a separate actuator.
 11. A robotic device comprising: a plurality ofsegments pivotally interconnected to form an elongated member; aplurality of drive track assemblies operably coupled to each of saidplurality of segments, said plurality of drive track assembliesgenerally disposed in pairs about a periphery of each of said pluralityof segments to provide traction at any position about said periphery; apower source; an articulating drive shaft rotatably driven by said powersource; and a power transmission system interconnecting saidarticulating drive shaft and at least a portion of said drive trackassemblies to drive said plurality of drive track assemblies.
 12. Therobotic device according to claim 11 wherein each of said plurality ofdrive track assemblies comprises: a continuous drive track; a drive gearoperably coupled to said power transmission system; a driven gearenmeshingly engaging said drive gear; and a track gear fixed forrotation with said driven gear, said track gear enmeshingly engagingsaid continuous drive track to drive said continuous drive track topropel the apparatus.
 13. The apparatus according to claim 11 whereineach of said plurality of drive track assemblies comprises: a continuousdrive track having an environment engaging outer surface and a rackedinner surface; a worm gear operably coupled to said power transmissionsystem; a first gear enmeshingly engaging said worm gear; a second gearenmeshingly engaging said first gear; a third gear enmeshingly engagingsaid second gear, said third gear having a drive shaft fixed thereto forrotation therewith; and a pair of driven gears fixed to said drive shaftfor rotation with said drive shaft, each of said pair of driven gearsengaging said racked inner surface of said continuous drive track todrive said continuous drive track.
 14. The robotic device according toclaim 11 wherein each of said plurality of segments is identical andinterchangeable.
 15. The robotic device according to claim 11, furthercomprising: a head segment coupled to one of said plurality of segments;a controller mounted in said head segment, said controller driving saidplurality of drive track assemblies; and a sensor system mounted in saidhead segment, said sensor system being in communication with saidcontroller.
 16. A robotic device for traversing obstacles, said roboticdevice comprising: a plurality of segments pivotally interconnected toform an elongated member; a plurality of drive track assemblies operablycoupled to each of said plurality of segments, said plurality of drivetrack assemblies generally disposed about a periphery of each of saidplurality of segments to provide traction at any position about saidperiphery; a power source; an articulating drive shaft rotatably drivenby said power source; a power transmission system interconnecting saidarticulating drive shaft and at least a portion of said drive trackassemblies to drive said plurality of drive track assemblies; a headsegment coupled to one of said plurality of segments; a controllermounted in said head segment, said controller driving said plurality ofdrive track assemblies; and a sensor system mounted in said headsegment, said sensor system being in communication with said controller.17. The robotic device according to claim 16 wherein each of saidplurality of drive track assemblies comprises: a continuous drive track;a drive gear operably coupled to said power transmission system; adriven gear enmeshingly engaging said drive gear; and a track gear fixedfor rotation with said driven gear, said track gear enmeshingly engagingsaid continuous drive track to drive said continuous drive track topropel the apparatus.
 18. The robotic device according to claim 16wherein each of said plurality of drive track assemblies comprises: acontinuous drive track having an environment engaging outer surface anda racked inner surface; a worm gear operably coupled to said powertransmission system; a first gear enmeshingly engaging said worm gear; asecond gear enmeshingly engaging said first gear; a third gearenmeshingly engaging said second gear, said third gear having a driveshaft fixed thereto for rotation therewith; and a pair of driven gearsfixed to said drive shaft for rotation with said drive shaft, each ofsaid pair of driven gears engaging said racked inner surface of saidcontinuous drive track to drive said continuous drive track.
 19. Therobotic device according to claim 16 wherein a pair of said plurality ofdrive track assemblies is disposed on each of four sides of each of saidplurality of segments to provide traction at any position about saidperiphery.
 20. The robotic device according to claim 16 wherein each ofsaid plurality of segments is identical and interchangeable.